Am probably not the only 1 feeling a little bit cross with #Orange atm ... like I have spare cash to increase my phone bill every month grrrr.

From January 8 2012, the company is to increase costs for those customers who agreed their deals before September 2011, blaming the price rise on rising inflation. The majority of Orange contract customers will forced to pay higher bills for the remainder of their contract – which could be as long as 24 months.

Orange has said it will not permit customers to cancel their contract as its terms state that inflation-linked price rises are allowed. This is despite Ofcom regulations that ban such action by operators and allow customers to terminate a contract when the terms are changed.

However, it is not clear whether Orange's stance would hold up if challenged by consumers.

Martin Lewis, founder of Moneysavingexpert.com, said: “This isn’t a clear-cut case – so predicting the outcome of any complaint is tough. However, for those who want to escape their contract, it is worth formally contacting Orange and telling it you believe the price hike is of ‘material detriment’ and you want to leave.

Mr Lewis pointed out that there was a slight chance the company would prefer to let some people go on an ad hoc, goodwill basis rather than risk having a large number of people complain to Ofcom.

“If the company doesn’t wilt, call Ofcom, as if enough people complain it will investigate, which would see a firm have to answer on the whole thing," Mr Lewis said. “However, this is about hoping it may work, but not planning your finances on it happening.”

A spokesman for Orange said: “We are confident that we continue to offer our customers great value and rewarding deals. All customers affected by the price increase will be contacted with full details.”

Orange is owned by Everything Everywhere, which also owns T-Mobile. However, T-Mobile said it had no plans to raise prices.